Party line telephone system



lDec. 6, 1949 w, HATTON PARTY LINE TELEPHONE SYSTEM Filed March 22, 1945HGENT- Patented Dec. 6, 1949 l ;;;1

PARTY LINE TELEPHONE SYSTEM William Hatton, Maplewood, N. J., assignorto International Standard Electric Corporation, New York, N. Y., acorporation of Delaware Application March 22, 1945, Serial No. 584,0601o claims. (ci. 179-17) This invention relates to automatic telephone Isystems, and has for an object to provide a simple and economicalarrangement for selectively ringing a called party on a multi-partyline.

Another object of the invention is to provide an improved arrangementfor controlling ringing voltages of different station-selectingcharacteristics and for impressing the selected ringing voltage over thecalled multi-party line.

A further object of the invention is to convert by an improved adaptercircuit the penultimate and nal selectors of an automatic telephonevswitching system from an individual to a multiparty line basis.

A still further object of the invention is to arrange the nal selectorsfor party line working on a terminal per station basis in a manner suchthat signaling for individual lines remains substantially the same.

In accordance with this invention, party lines are accommodated in thebanks of the final selectors on a terminal set per station basis byassociating with the terminal sets and with the party line a relayadapterV circuit, which is provided with a particular identifyingvoltage for each of the stations and which in response to a call isadapted for initiating the selection in one of the selectors of thecharacteristic ringing voltage that is to be impressed over the line.

A feature of the invention resides'in a nal selector switch in which the(a) and (b) or talking terminals of the terminal sets allocated to aparty line are connected to a two-relay adapter circuit which determinesthe selection of the proper ringing frequency.

A still further feature ofthe invention resides in a selector switch inwhich a particular one of a plurality of different ringing voltages ofstation-selecting characteristics is arranged to be impressed over asubscribers line in response to a particular voltage indication from theterminal set engaged by the final selector.

Other features of the invention relate to circ uit improvements whichWill be apparent from the following detailed description of the drawing,which shows by means of the usual circuit diagrams a sufficient amountof apparatus to enable the invention to be described and understood.

The invention is illustrated in an automatic telephone system of theharmonic ringing type employing rotary-type line finder and selectorswitches including associated sequence switches; but it is to beunderstood that the invention is not to be limited in its application tothe specific arrangement shown.

Referring to the drawing, there is shown a multi-party line having foursubscriber stations A, B, C and D associated therewith, a two-relayadapter circuit associated with four terminal sets i in the bank of afinal selector switch, and a penultimate selector switch including thepertinent sequence switch cams, harmonic ringing supply having the usualdistinguishable frequencies, and relays for controlling the frequencyselection of said ringing supply.

The subscribers stations are of the type normally employed in automatictelephone systems and each includes a dial for use in obtainingconnections with any other station. Four stations are shown connectedover one line to the exchange, the line circuitat the exchangecomprising the usual cut-olf relay and line relay, the latter of whichis actuated when any of the above subscribers initiates a call. Asusual, the line is also multiplied in the banks of a group of linefinders. As mentioned hereinbefore, the line finder and selectorswitches are of the wellknown rotary type and a description of thedetails thereof is not required for an understanding of the presentinvention. A system of this type is fully described and illustrated inElectrical Communication, Volume 3, published in the U. S. by GeraldDeakin, January 1925, pages 153 to 189. The terminals of the finalselector are arranged on a terminal-per-station basis, that is, aseparate set of terminals is provided in the selector switch for eachparty line subscribers station.

In order to instal a party line, the terminal sets in the banks of thefinal selectors allocated to the party line stations are connected to aparty line` assembly frame to which is also connected the party lineitself and a two-relay adapter circuit, comprising marking relay l andline-connecting relay l2, as shown. It Will be noted that the contacts aand b of the terminal set of party A are connected directly to the partyline, but the a contacts of parties B, C, and D are connected overrespective back contacts of relay III to line conductor I3 and the bcontacts of parties B, C, and D are connected in multiple over a frontcontact of relay l2 to complete the connection to line conductor Il. Thetest contact terminals c for al1 four parties are multipled together forobvious reasons. While the invention has been disclosed with referenceto a four-party line, it is apparent that the invention may be readilyapplied to party lines having a greater or lesser number of stations byanyone skilled in the telephone switching art.

tion A, the call having been routed to the Final l selector in knownmanner, which has found the called party line to be free, andassume-further`r that the sequence switch has reached position Ij. Underthis assumption it will be recognized that positive battery to relay I4in the Penultimate selector to energize same; and at the lowermost frontcontact connects ground to relay I2 in a circuit that can be traced fromgrounded positive battery through winding and bottom back contactthereof, bottom front contact of relay Ill, and thence through windingof relay I0 to ground. Relay I2, however, does not operate at this timein view of the resistance 2| of the Penultimate selector being inparallel with the Winding thereof which is of relatively highresistance.

The circuit for the operation of relay It may s be traced from groundedpositive battery through the bottom set of terminals, that is, for partyA, has been seized by the Final selector, terminals a, b thereof beingconnected directly to the lineconductors I3, II, respectively. It willbe further recognized that operationof the sequence switch camy K'of thePenultirnate. selector has no eife'ct with respect to thev selection ofringing current up to position I2, inclusive, inasmuch, asthe terminalsa, b are4 not routedv through relays.

Il), I 2.. However, when sequence switch cam K reaches its. 13thposition, ringing current is irnpressed over theline conductors II, I3to signal` the call'edsubscriber A. This. circuit can be traced fromgrounded 16% cycle ringing supply through the right back contact ofrelay I5, left back contact of relay I4;V winding of relay I8, lowerand,v upper left springs of sequence switch cani K', brushes andterminals of Penultimate and.l

Final selectors, respectively,.and thence over conductor bandlinec'onductor IfI to the subscribers.

set A where it is returned over line conductor I3 and conductor a,through terminals and brushes:

of Final and Penultimateselectors, respectively,

left springs of sequence switch cam O, and thence.

to ground over the make contact of relay I9,

which had been operated previously through a.

circuit not required to be described` herein. Ringing continues. overthe line until the subscriber answers4 or until the sequence switch camK reaches position I5..

Upon subscriber Av answering, talking battery (not shown) is connected.to the called line and the sequence switch: of ther Penultimate selectorpasses in the usual manner to. position I and remains there during;thezconversational period. After the calling subscriber hangs up, thesequence switch passes to position I5 and` thence to position IL'I uponthe calledgsubscriber hanging up. The sequence switch. then continues toposition I afterwhich it returns-.to its normal position in readinessfor an'othercall. It is readily apparent frornthe above that theaddition of the relay adapter circuit toftheFinal selector has nomaterialV effect uponthe manner in which party A is selectively rung.

Assuming now that any of the other three parties is to be called, forexample, partyD, and the appropriate setl of terminals` has been seizedby the Final selector, then in. this instance upon the sequence switchofthePenultimate selectorV reaching position IUI/2, marking relay I5 isenergized in a circuit that.. can be traced. from grounded batterythrough.` the two upper springs of sequence switch cam.P,.resistance 2|,brushes and terminals ofPenultimate and Final selectors, respectively,over lead b, via upper back Vcontact of line-connecting relay I2,andthence to ground through the winding offrelay' I0. In energizing,relay Il! at its uppermost front contact connects left winding thereof,lower right and upper left springs of sequence switch cam S, brushes andterminals of' Penultimate and Final selectors, reg.spect ively, overlead a, through uppermost make contact of relay I0 and resistance 22 tobattery and-ground. Relay I4, in operating,` locks itself in a circuitthat can be traced from grounded positive batterythrough right frontAContact thereof and to ground: over.l right springs. of sequence switchcam J ofthe Penultimate selector. Relay I6 also, in operating, closesits. left front contact and. connects it' through the leftback Contactof relay I5 to a. harmonic ringing supply source of 50 cycles. Nomaterial change in. circuit operation' occurs during thev passage of.the sequence switch from'. positions |01@ to I2. However, uponpositionI2 being reached the upper and lower left springs of sequence switch.cam S close and provide an energizing circuit for relay I5, which can betraced froml. ground through the right winding thereof, left springs ofsequence switch k cam S, brushes and terminals of Penultimate and Finalselectors; respectivelyv over lead a through uppermost front contact of'relay IQ, and thence through` resistance 22v tol positive battery andground. Relay I5, in operating, at its right front contactconnects-331/3- cycle harmonic ringing current thereto but this isineffective inV view of the operation. of relay I4.; at its outer-mostleft front contact provides a locking circuit', which canv be tracedfrom positive grounded battery through 'the left winding thereof toground through the righ-t springs ofsequence switchr cam J; at -it'sinner left front contact connects harmonic 'ringing current of 662/3vcycles thereto, which is ineffective until sequence switch cam K reachesposition I3- It is thusf seen that the marking potentialA of positivebattery provided by markingrelay` IU, which potential is characteristic'of party DLis effective by operation of relays- It: and I5to'causeselection of a harmonic ringing frequency ofv 66% cycles persecond.

vIt is-to be noted 'that when the sequence switch leaves position I2thatthe above-traced energizing-battery via 'sequence switch cam P forrelay Ill2 is disconnected. However, inasmuch as energizingbattery,throug h the winding of relay i2, is also connected' to thewindingV of relay IU, this relay remains energizedl momentarily andrelay I2 operates, in the hereinbefore-traced circuit. Relay I2, inoperating, opens. the energizing circuit for. relay Ill: 'at 'its lowerback contact and.

5` ringing circuit-can be traced from grounded ringing supply of 66%cycles over the left inner front contact f relay I5, left front contactof relay I4, winding of relay I8, springs of sequence switch cam K, overconductor b through the Penultirnate and Final selector switches, upperfront contact of relay I2, over line conductor Il to subscribersstation'v D, back over the subscribers loop including line`conductor I3,uppermostI back contact of relay -IIl, back over conductor a and throughFinal and Penultimate selector switches, left springs of sequence switchcam O, and front contact of relay I9 to ground. The remainder of thecall proceeds in a manner similar to that described for party A, exceptthat line-connecting relay I2 also releases upon the parties hanging up.

A similar procedure obtains in selecting the characteristic ringingvoltage for party C. In this instance, when the selector terminals ofparty C have been seized and marking relay I operated, the upperintermediate front contact has ground placed on the a wire, which,obviously, cannot operate grounded winding of relay I5. However, thisground does operate the left winding of relay I4, which energizes in amanner above-described and which furnishes the called line with 50 cycleharmonic ringing current.

Similarly, if party B is to be called, and assuming the terminalsthereof have been seized by the Final selector and relay I0 to have beenoperated in the above-described manner, then negative battery throughresistance 24 is connected via the lower intermediate front contact ofrelay I0 in succession to relays I4 and I5 of the Penultimate selector.Obviously, relay I4 cannot operate but relay I5 does, in an obviouscircuit that does not require tracing, with the result that harmonicringing voltage of 331/3 cycles is impressed upon the subscribers linecircuit.

It will be appreciated that the terminal sets allocated to a party lineneed not be adjacent to one another in the terminal banks of nalselectors.

While this invention has been shown and described as embodying certainfeatures merely for the purpose of illustration, it is clear to anyoneskilled in the machine-switching art that many modifications arepossible without departing from the spirit of the invention and thescope of the appended claims.

What is claimed is:

1. In a telephone exchange system, a party line having a plurality ofstations associated therewith, a final selector having an individual setof terminals for each one of said stations, a plurality of sources ofringing current of different characteristics, sources for a plurality ofmarking signals, a relay associated with said party line, means forenergizing said relay upon the seizure of said line by said nal selectorover one of said sets of terminals, means controlled by said relay forconnecting one of said marking signals to a terminal of said one set ofterminals, and means responsive to the marking signal thus connected forselecting a particular one of said sources of ringing current forapplication to the party line.

2. The system according to claim 1, and a second relay common to saidparty line and controlling the circuit of the rst relay.

3. The system according to claim 2, an energizing circuit for the secondrelay including a contact of the first relay, and a holding circuit forthe second relay including a terminal in any one of the sets belongingto the party line.

4. The system according to claim 1, and in which one niarking signal ispositive and another marking signal negative potential, and the meansresponsive to the marking signal comprising twol relays one responsiveonly to positive and the other only to negative potentials.

5. The system according to claim 4, and in which the sets of terminalsinclude talking terminals to which said marking signals are connected,and said two relays are connected in multiple over a inal selector witha talking terminal of eachcalled party line station.

6. In a telephone exchange system, a party line having four stationsassociated therewith, a iinal selector including four individual sets ofterminals for said line, four sources of ringing current of differentcharacteristics, sources for two marking signals, a relay associatedwith said party line, means for energizing said relay upon the seizureof said line by said nal selector over any one of three sets ofterminals, a front contact for said relay to connect one marking signalto one of the three sets and a second front contact for said relay forconnecting another marking signal to another one of said three sets, andmeans variably operable depending on the presence or absence of themarking signals for selecting a particular one of said sources ofringing current for application to the party line.

'7. In a telephone exchange system, a party line having a plurality ofstations associated therewith, a final selector having an individual setof talking and test terminals for each one of said stations, meansincluding said final selector for extending a calling line to any one ofsaid sets of terminals, a plurality of sources of ringing current ofdifferent characteristics, rst and second relays associated with saidparty line, back contacts for the second relay for connecting a talkingterminal of all but one of said sets of terminals to the energizingwinding of the first relay, front contacts for the second relay forconnecting the last-mentioned talking terminals to one of the conductorsof said party line, sources of a plurality of marking signals, frontcontacts for the rst relay for connecting one of said marking signals toone and the second marking signal to a second talking terminal of saidall but one of said sets of terminals, and means responsive to saidmarking signals for selecting a particular one of said sources ofringing current for application to the called party line.

8. The system according to claim 7, and an energizing circuit for thesecond relay controlled by front contacts of the iirst relay.

9. In a telephone exchange system, a plurality of party lines eachhaving four stations associated therewith, a final selector havingindividual sets of talking and test terminals for each party linestation, means including said nal selector for extending a calling lineto any one of the sets of terminals of the called party line, foursources of ringing current of different characteristics, a rst and asecond relay associated with each party line, back contacts for thesecond relay for connecting a talking terminal of three of said sets ofterminals to the energizing winding of the first relay of the calledparty line, front contacts for the second relay for connecting thetalking terminals of the three sets to one of the conductors of thecalled party line, sources of a plurality of marking signals common tothe party lines, front contacts controlled by the second relay forconnecting one of said marking signals to one and the second markingsignal to a second talking terminal of said three sets of selecting .aparticular xmeofaidsOurces'of -ring- The following references vare ofrecord `in 'the ing current for amilicaition @to he v.called party le ofthis patent: line. 5 Y

F10. The system accordingto claim 19. an ener- UNITED STATES PATENTSgizing circuit for the second :relay controlled in Number Name Date airont contact ofthe @sscciatedirst relay, and 1,565,727 Eiendly Dec. 15,1925 a holding `circuit for :the s econd relay including 1,849,088Hovland Mar. 15, 1932 the test terminal of anyrof'the four sets. 1o1f970,337 Pope Aug. 14,1934v

